Julius kauffmann



UNITED STATES PATENT OFFICE.

.IULIUs KAUFFMANN, or OROELLWITZ, NEAR HALLE-ON-THE-SAALE, PRUS- SIA, GERMANY.

METHOD OF CONVERTING STRAW INTO BLEACHED PAPER.

SPECIFICATION formingpart of Letters Patent No. 229,254, dated June 29, 1880.

I Application filedMarch 23, 1880. (Specimens) To all whom it may concern:

Be it known that I, JULIUs KAUFFMANN, of Groellwitz, near Halle-oi1-theSaale,in the Empire of Germany, have invented a new and 5 Improved Method of Converting Straw into Bleached Paper, of which the following is a specification.

Bye, wheat, oat, or barley straw is cleared of weeds by sorting, and is then, by means of a chaff-cutting machine, cut into chafi about one to one and a half centimeters long. The straw so cut is then put into a revolving boiling -pot, in which it is boiled for about four hours under a steam-pressure of from four to four and a halt atmospheres, and with the use, for every one hundred kilograms of straw, of about thirteen kilograms of caustic soda containing seventy-one percent. of pure soda,

or of twenty-two kilograms of calcined soda holding ninety per cent. made caustic. After the boiling process has been completed the lye is drawn off, and the boiled straw is cleaned of dirty lye by twice allowing cold water to flow upon it and drawing the same off. The

straw is then taken to a washing-engine, in which it is washed for an hour by means of washing-cylinders, the sieve of which has about sixty meshes per square inch.

By means of a centrifugal machine the washed straw is deprived of so much water that it retains only the quantity required for the action of the chlorine gas, or about seventy per cent. of water. In order to attain this object it is necessary, for the sake both of 3 5 enabling work to be conducted on a large scale and of obtaining loose cakes of straw, to use sieves in the centrifugal machines which have no more than fifty holes per square inch.

The straw cakes now formed are exposed to 4.0 the action of chlorine gas. This is done in bleachingchambers of known construction, the cakes being so piled up in them 011 hurdles or latticed frames that close packing is avoided. The quantity of chlorine gas to be used for every one hundred kilograms of unboiled straw amounts to that generated from about twenty-three kilograms of hydrochloric acid having a density of 22 Baum, and a corresponding quantity of pyrolusite holding 5o seventy per cent. of peroxide of manganese. Inferior grades of pyrolusite, which absorb hydrochloric acid, owing to their high percentage of iron and the consequent formation of oxide of iron and chloride of iron, call for a corresponding increase in the quantity of hydrochloric acid to be used.

After this bleaching process the acids generated by it are removed by washing in a washing-machine. If the bleaching with gas should not have completely broken the fiber, this may be done by suitable apparatus or machinery of known construction, either before or after the final bleaching, which is effected by means of two kilograms of chloride of lime holding thirty-five per cent. for every one hundred kilograms of straw to be bleached.

Pine Wood has, before my invention, been deprived by chemical means of the substances to be extracted from it, and is thus converted into fibers or cellulose. in a similar way it is, in the present case, the aim of theintense action of the chlorine gas to destroy the substances enveloping the straw fiber, and thus to separate ita result which is not obtained by boiling with caustic soda.

It is of great imrmrtance, as affecting the attainment of a long and flexible straw fiber, that the use of mechanical means like cutting or grinding surfaces be limited as much as possible.

The method described is therefore remarkable for the production of a long, elastic, extremely white fiber, thus admitting of more extended use for paper, diminishing the adhesion to the presses during the work on 85 the paper-machine, and causing it to appear smooth in the paper.

If mixed with cotton fiber and with about ten per cent. of barytes, the resistance to tearing which the straw fiber imparts to paper is o sufiicient to prove the toughness of the fiber.

I claim- The process of preparing straw for the manufacture of paper by first cutting it. then boiling it in caustic soda, then separating it 5 from thelye,forming it into cakes, and finally destroying the envelope of and bleaching the straw fiber by exposure to chlorine gas, substantially as specified.

This specification signed by me this 20th I00 day of February, 1880.

JULIUS KAUFFMANN. 

